The definitive, scientific answers to 20 health questions everyone has

Does cough syrup work?

Short answer: No

It’s been a while since doctors came to agree that most over-the-counter cough medicines don’t work. In 2014, Australian researchers published similar conclusions that the syrups typically contain doses of codeine and antihistamines that are too small to be effective and can be harmful for children.

Prescription cough suppressants such as levodropropizine, however, might have a better shot. 

Does olive oil prevent heart disease?

Short answer: Yes

As if you need more of an excuse to put olive oil on everything, scientists have found a connection between eating more olive oil and a lower risk of coronary artery disease. Studies that are happening right now are testing out how a Mediterranean diet rich in olive oil compares to low-fat diets when it comes to heart disease recurrence.

In general, olive oil’s antioxidant and anti-inflammatory effects have also been well documented. And in a study of older women published in 2015 in the medical journal JAMA, Spanish scientists found that a Mediterranean diet supplemented with extra olive oil appeared to help reduce the participants’ risk of breast cancer when compared with two other groups of women on a low-fat diet and a Mediterranean diet supplemented with nuts.

Do sugary soft drinks lead to diabetes?

Short answer: Yes

Sugary drinks are associated with Type 2 diabetes, according to a 2010 analysis of studies on the relationship. Compared with those who had less than one sugary beverage a month, those who had about one to two servings a day had a 26% greater risk of developing Type 2 diabetes, the analysis found. 

And it’s not just diabetes —excessive sugar consumption can lead to a host of problems. For example, sugar-sweetened beverages are also associated with weight gain and diabetes, a 2006 review that looked at 50 years worth of studies found. 

The difference between SPF 15, 30, and 50 isn’t as linear as you might expect. SPF 15 blocks out 93% of UVB rays, while bumping up to 30 gives you 97% protection (not necessarily double). Going up to 50 boosts you up to 98% protection. And, once you get past that point, it’s only going to give you incrementally better protection.

The Food and Drug Administration, which is in charge of regulating sunscreen, says the more important factor is going for a sunscreen labeled “broad spectrum.” That means the sunscreen’s protection against ultraviolet A rays, or UVA, is proportional to protection against ultraviolet B rays. Yes, you can go up to 50 SPF and be safer, but as long as you stay above SPF 15 with the broad spectrum, you should be set. Just be sure to reapply frequently (the FDA suggests every two hours or so).

Is the MSG in Chinese food likely to give you a headache?

Short answer: No

MSG, a savory food additive that some say causes headaches, chest pain, flushing, and numbness, has never been scientifically proved to cause any of those symptoms. A 2006 analysis found that while there had been reports of MSG sensitivity, in placebo-controlled studies the sensitivity has never been demonstrated.

Is drinking fruit juice as good for you as eating fruit?

Short answer: No

You don’t want to lose the fiber that’s in the peels and pulp of the fruit — and let’s face it, most of us don’t get enough fiber as it is. A 2014 study comparing orange juice to oranges, however, suggested that the juice form might be able to unlock nutrients like flavonoids and carotenoids compared with whole oranges, though that doesn’t overrule the lack of fiber.

So if you’re looking for the best of both worlds, opt in for pulp so you at least get a little bit. 

Are all wheat breads better for you than white bread?

Short answer: No

Not all wheat breads are created equal, so take note. Though most white bread is made with refined grains that skip out a lot of the fiber and nutrients, there are whole-wheat white breads that are just as healthy as whole-wheat breads.

Regardless of your color preference, make sure you’re getting whole wheat: bran, germ, endosperm, the whole package.

Can a hot tub make me sick?

Short answer: Yes

Hot tubs are a really great breeding grounds for germs. According to new data on more than 84,000 inspections released in 2016 by the Centers for Disease Control and Prevention, 1 in 8 public swimming places (pools as well as hot tubs) had to be shut down because of health and safety violations. The most common reasons had to do with improper pH levels or disinfectant concentrations.

Many outbreaks in public pools and hot tubs are caused by Cryptosporidium, a parasite that can cause gastrointestinal illness and is pretty resistant to chlorine. But that doesn’t mean you should steer clear of the jets of hot water or the local pool during the summer; just try not to swallow a bunch of water and know some of the warning signs. 

Do eggs raise cholesterol levels?

Short answer: No

Egg lovers can rejoice: In 2015, the USDA dietary guidelines let eggs off the hook. Eggs contain a lot of cholesterol, which gave them the reputation of being unhealthy. There’s evidence, however, suggesting that the cholesterol present in foods doesn’t have an effect on cholesterol in blood (which can lead to heart problems).

Can you drink too much water?

Short answer: Yes

If you put too much water in your body (we’re talking multiple water bottle amounts while doing extreme exercising), your kidneys aren’t able to process it all, which dilutes the amount of minerals in the blood. That gets to be a problem when sodium levels get low, a condition called hyponatremia.

The way to prevent it? Drink electrolyte-replacing drinks while working out instead to make sure your body has enough to keep on moving.

Can yogurt ease digestive problems?

Short answer: Yes

In theory, eating bacteria-filled yogurt is a good idea. After all, a gut teeming with healthy microbes is a happy one. Bacteria and other critters living in our intestines help break down food, so the idea is that if you can add more bacteria through probiotic yogurt, you may be able to keep things running smoothly.

But, as science writer Ed Yong explained to Business Insider in October 2016, the probiotic yogurts we have today might not actually be able to colonize in our gut — likely because there are too few in the yogurt to begin with.

“The idea of taking beneficial microbes is a very sound one,” Yong said. “But I think we need to get much savvier and smarter about picking microbes that are going to do well inside us.”

Yogurt also packs in an unexpected amount of sugar, so keep that in mind as you consider it as a snack.

Do whitening toothpastes whiten teeth more than regular toothpastes?

Short answer: No

As fun as “scientifically proven” labels on toothpaste containers are, they’re not entirely accurate. According to the American Dental Association, whitening toothpastes may be able to do something on the surface level. To get to the deep-down stains, you have to opt into more extreme treatments like bleaching. Plus, whitening toothpastes have shown to be more toxic than regular toothpastes, so it might not be worth the trouble.

Is it safe to microwave food in plastic containers?

Short answer: Yes

… but only if it’s marked “microwave safe.” A 2014 study found that phthalates, a group of chemicals that make plastic flexible and are a possible carcinogen, migrated from plastic to food that was heated in the container more easily after prolonged use. Containers marked microwave safe shouldn’t contain these chemicals and other suspected carcinogens. 

Is red wine better for you than white wine?

Short answer: No

This is one of those findings that changes all the time. In 2015, Vox analyzed more than 30 studies about the effects of red wine and found that while drinking a small amount of alcohol each day (one drink for women, two for men) is associated with a lower risk of heart disease and higher life expectancy, red wine in particular doesn’t influence that very much. Go too overboard, and you’re also looking at some problems.

If you’re looking purely at nutritional content, red wine might win out of white because it tends to have less sugar and more minerals. 

Is bottled water better for you than tap water?

Short answer: No

Unless you live in an area with known unclean drinking water, opting for bottled water isn’t doing you much good. In fact, you could be missing out on fluoride, which is important for keeping teeth from decaying. And it’s not doing the environment any good at all.